岩土力学
巖土力學
암토역학
ROCK AND SOIL MECHANICS
2013年
5期
1508-1514
,共7页
颗粒材料%剪胀性%孔隙胞元%离散元法%局部化
顆粒材料%剪脹性%孔隙胞元%離散元法%跼部化
과립재료%전창성%공극포원%리산원법%국부화
granular materials%dilatancy%void cell%discrete element method%localization
剪胀性是颗粒材料在加载过程中表现出来的重要变形特性.以孔隙胞元描述颗粒材料内部结构的最小单元,通过对单个孔隙胞元进行剪切受力分析,探讨了剪切过程中颗粒材料体积的改变对应力比和单个孔隙胞元形状的依赖关系,解释了排列密实的颗粒材料在剪切过程中先压缩后剪胀的微观机制.用离散元数值模拟得到了在双轴剪切过程中单个孔隙胞元形状以及孔隙胞元体积变形的演化过程.离散元数值结果表明,加载过程中孔隙胞元形状由初始各向同性到沿大主应力方向变大变长、体积变形先压缩后膨胀,并且体积变形在加载过程中存在局部化现象,体积变化大的孔隙胞元在较大变形时,排列成倾斜的窄带.综合孔隙胞元的受力分析和离散元数值结果表明,致密排列颗粒材料的剪胀性与微观尺度上孔隙胞元的几何结构及其内部的力链传递方式密切相关.
剪脹性是顆粒材料在加載過程中錶現齣來的重要變形特性.以孔隙胞元描述顆粒材料內部結構的最小單元,通過對單箇孔隙胞元進行剪切受力分析,探討瞭剪切過程中顆粒材料體積的改變對應力比和單箇孔隙胞元形狀的依賴關繫,解釋瞭排列密實的顆粒材料在剪切過程中先壓縮後剪脹的微觀機製.用離散元數值模擬得到瞭在雙軸剪切過程中單箇孔隙胞元形狀以及孔隙胞元體積變形的縯化過程.離散元數值結果錶明,加載過程中孔隙胞元形狀由初始各嚮同性到沿大主應力方嚮變大變長、體積變形先壓縮後膨脹,併且體積變形在加載過程中存在跼部化現象,體積變化大的孔隙胞元在較大變形時,排列成傾斜的窄帶.綜閤孔隙胞元的受力分析和離散元數值結果錶明,緻密排列顆粒材料的剪脹性與微觀呎度上孔隙胞元的幾何結構及其內部的力鏈傳遞方式密切相關.
전창성시과립재료재가재과정중표현출래적중요변형특성.이공극포원묘술과립재료내부결구적최소단원,통과대단개공극포원진행전절수력분석,탐토료전절과정중과립재료체적적개변대응력비화단개공극포원형상적의뢰관계,해석료배렬밀실적과립재료재전절과정중선압축후전창적미관궤제.용리산원수치모의득도료재쌍축전절과정중단개공극포원형상이급공극포원체적변형적연화과정.리산원수치결과표명,가재과정중공극포원형상유초시각향동성도연대주응력방향변대변장、체적변형선압축후팽창,병차체적변형재가재과정중존재국부화현상,체적변화대적공극포원재교대변형시,배렬성경사적착대.종합공극포원적수력분석화리산원수치결과표명,치밀배렬과립재료적전창성여미관척도상공극포원적궤하결구급기내부적력련전체방식밀절상관.
@@@@The shearing induced dilatancy is an important deformation characteristic of granular materials during loading process. As the minimal unit to remain stable under external load, void cell is used to characterize the internal structure of granular materials. Based on the shear process of the individual void cell, it is found that the volume change of void cell is dependent on the stress ratio and the shape of void cell. It is explained the microscopic mechanism of the phenomenon that the dense granular materials compress first and then dilate. The evolutions of the shape of the individual void cell and volume deformation in them during biaxial shear test are simulated by using discrete element method (DEM). The results show that, the void cell is enlarged along the direction of the maximum principal stress and the volume deformation in the void cell compression first and then dilate as biaxial compression proceeds. Moreover, localization phenomenon is observed in the volume deformation in local void cells from the numerical results, i.e. voids with large dilatancy exhibit in the form of oblique bands at large deformation stage. The mechanical analysis of individual void cells and DEM results of dense granular array show that dilatancy of granular materials is dependent on the microscopic geometry fabric and the transmission of the force in them.
